MELANEEPES. 411 



Mr. Hargitt ; so that it includes all the species usually placed in Centurus. The two 

 groups are chiefly, if not only, separated by colour-characters, and these, again, are con- 

 nected by such species as Melanerpes pucherani. 



As in Chloronerpes, Melanerpes has a short tarsus, which is less than the middle toe 

 .and claw and less than the outer toe (reversed) and its claw ; but the wing is consider- 

 ably longer, and the style of coloration very different. 



The Mexican and Central- American species may be divided into three groups as 

 follows : — 



a. Back uniform black, glossed bluish or green. = Melanerpes (type M. erythrocephalus) . 



/3. Back black, with a broad median stripe of pale dxab. 



y. Back black, distinctly barred with white. = Centurus (type M. carolinus) . 



The first of these groups is represented by M. formicivorus ; the second by M. chrys- 

 auchen ; the third by M. pucherani, M. wagleri, M. ruhriventris, M. aurifrons (and its 

 allies), M. uropygialis, M. elegans, and M. hypopolius — in all twelve species, the whole 

 genus containing about thirty-three species, more or less distinct. Of these only four 

 are found in North America, of which M. carolinus reaches Canada. Each of the larger 

 Antilles, and several of the smaller islands, as well as some of the Bahamas, have species 

 -of their own. The rest belong exclusively to South America, and mostly appertain to 

 group j3 ; South Brazil and Western Argentina being the furthest points reached. 



The chief memoirs on Melanerpes are Mr. Hargitt's ' Catalogue of Picidse in the 

 "British Museum,' which treats of the genus as a whole ; Dr. Cabanis's notes on Centurus 

 in the 'Journal fiir Ornithologie ' for 1862; and Mr. Bidgway's review of the genus 

 Centurus in the 'Proceedings of the United States National Museum' for 1881. On 

 the whole, we have followed Mr. Hargitt's arrangement, which was based almost entirely 

 upon the series of skins gathered by us for the present work. 



One point as regards the inter-relationship of some of the species of Melanerpes calls 

 for special notice, and that is the intergradation or blending which seems certainly to 

 take place along the boundary-lines of the ranges of some of them. This fact induced 

 Mr. Eidgway to use trinomials largely in their nomenclature. We have thought it 

 best to adhere to the old plan of binomials wherever a form proved to be definite. over 

 a certain area, and also where the modifications seem to indicate only a general tendency 

 towards a not thoroughly established character. We have not attempted to differentiate 

 by name the intermediates between otherwise fairly precise forms. 



Mr. Eidgway's plan has this difficulty, which is well illustrated by his treatment of 

 M. aurifrons and its allies. Thus we have M. aurifrons, M. a. santacruzi, M. a. dubius, 

 M. a. hoffmanni, and subsequently M. santacruzi pauper. Now the connection between 

 M. aurifrons and M. dubius, on the one hand, and M. hoffmanni, on the other, is cer- 

 tainly not direct, but through M. santacruzi. Therefore, to be thorough in this matter 

 of names, we ought to read M. aurifrons santacruzi dubius, M. a. s. hoffmanni, and 



52* 



